Marine chronometer double track escape and projection system



March 21', 1950 Filed Dec. 10, 1945 G. G. E E A MARINE CHRONOMETER D BLETRACK ESCAPE NSl T 2,501,266

AND PROJECTION SYSTEM 5 Sheets-Sheet l INYENTORS. g:

March 21, 1950 G. G. ENSlGN TAL 2,501,266

, MARINE CHRONOMETER nous TRACK ESCAPE AND PROJECTION SYSTEM Filed Dec.10, 1945 3 Sheets-Sheet 2 BY (24% ,M

evn. Ka y h ATTYJ,

March 21, 1950 G. G. ENSIGN ETAL 2,501,266

MARINE CHRONOMETER DOUBLE TRACK ESCAPE AND PROJECTION SYSTEM Filed Dec.10, 1945 3 Sheets-Sheet 3 INVENTORS 6524 6? 9 BY 8 74. J44 M 9 FD/(wATI'YS.

Patented Mar. 21, 1950 UNITED STATES PATENT OFFICE MARINE CHRONOMETERDOUBLE TRACK ESCAPE AND PROJECTION SYSTEM Application December 10, 1945,Serial No. 633,946

3 Claims. 1

This invention relates to chronometer escapements and comprisesstructures for assuringaccuracy of timekeeping and permitting correctand easy adjustment of these parts preliminary to service therefor.

One of the features of this invention is the provision of an escapementof the so-called chronometer type, in which different parts are employedfor delivering the impulse to the balance wheel and for the unlocking orrelease of the escape wheel, and in which different parts of the escapewheel are utilized for these respective duties so that wear effectsresulting from long service will not lead to inaccuracy in the timing.

Other features of the invention reside in the provision of a detentsystem which is adjustably supported and can be manipulated byadjustment means for assuring close and accurate setting of the detentfor engagement by the discharge stone: and in which the shock of anescape tooth upon the locking stone is taken by a couple of forces.

A further feature of the invention is a provision of an escapementsystem by which the cooperating parts of the escape wheel, impulseroller and detent are so positioned in such relationship to theirsupports that a beam of light can be passed through the escapement forrevealing the relative position of these parts when stationary, andtheir cooperation while in motion.

With these and other features as obiects in view, as will appear in thecourse of the following description, an illustrative form of theinvention is shown in the accompanying drawings inwhich:

Figure 1 is a general view of the train plate of a chronometer movement,including an escapement unit of an illustrative removable type.

Fig. 2 is a top view of this escapement unit, on a, larger scale.

Fig. 3 is a sectional view substantially on line 3--3 of Figure 2.

Figure 4 is a sectional view substantially on line 4--4 of Figure 3, forillustrating the detent action.

Figure 5 is' a sectional view" substantially on line 5--5 of Figure 4,to show the detent assembly.

Figs. 6 and 7 are fragmentary views'on a yetlarger scale, respectivelyillustrating the effects of wear upon the escapement teeth by theactions of the impulse and locking stones.

Figure 8 is a diagram of a projection system for inspection andadjustment.

In these drawings, Fig. 1 illustrates a chronometer movement having a,pillar plate Ill and a train plate H. The winding stem and ratchet I2are connected to the spring barrel I 3 which is positioned as usualbetween the plates ill, II. This spring barrel can be connected by achain to a fusee mounted on a shaft M, whereby to drive a clock trainwhich may be of the usual type and includes a fourth wheel [5a (Fig. 5)supported by a stair in the usual way.

In this illustrated form of the invention, a removable escapement unitis employed, including the top piece or balance cook 25, the middlepiece or escape plate 26 and a bottom piece or escape cook 21 (Figs 1, 2and 3) which together support the parts for the balance assembly, theescape assembly, the detent assembly, and the other structures which aredriven from the fourth wheel idol of the train and which serve toregulate the movement of the train. This removable escapement unit issecured to the train plate it by a screw iii, and is also securedthereto by a screw ll which may extend into a pillar, as

set out in the copending application of Ensign,

Lawson, Schaefer and Wochos, Serial No. 594,570, filed May 18, 1945, nowPatent 2,419,768, dated April 29, 1947. The train plate II has a roughlytriangular cut-away portion which is filled by the escape plate 26: andthe balance cock 25 is of greater peripheral dimension so that thesecuring screws it, I! pass through it into the train plate 1 i toprovide a strong and rigid structure.

The illustrated form employing the three pieces, being the balance cock25, the escape plate 26, and the escape cock 2! in the removable unit,has the escape pieces 26, 21 secured by screws 29, and this sub-assemblyconnected to the piece 25 by the screw 30. Dowels 28 assure the accuracyof alignment of the pieces.

The balance staff 32 is supported in the jewel bearings 33, 34respectively mounted in the bal ance cock 25 and the escape cook 21:each hearing having a hole stone and an end stone. Above the staffcollar 35 is a bushing 35 upon which rests the spoke member 31' of thebalance wheel 13W, this spoke member 31 being tightly fitted to thestafi. The balance wheel is formed with a rim provided by thebi-metallic arms 46 upon which are adjustably positioned the weights 4|which contribute a large part of the inertia mass of the balance wheeland provide, by their angular spacing on the thermally responsive armsrelative to the spoke member 31, a compensation for temperaturevariations. The gross adjusting nuts 42 are mounted on the screws G3secured to the balance rim at the connections to the spoke member 31:each nut 42 has a slit nearly dividing it with the parts forced out oftrue axial alignment to provide a lock against accidental movement. Thefine adjusting nuts 44 of smaller size are mounted on the screws 45which are diametrically opposed for poising and are located close to thescrews 43.

The hairspring 50 is of helical shape, with its upper fixed end pinnedto the stud la on the top piece 25, and the lower vibrating end pinnedto the balance spring collet 5|b which is tightly fitted on the staff32.

Below the collar 35, the staff 32 has the im pulse roller 52 mountedthereon and supporting the impulse stone 53; and also the dischargingroller 54 with the discharging stone 55. The impulse roller 52 has apassing hollow 56 which with the stone 53 is counterbalanced b the hole57: and has a tight fit on the stair. The discharge roller 54 has atight friction fit on the staff, so that its angular position can beshifted but sufficiently tight so that an adjusted position is retained.

The escape staff 58 is carried by the jewel bearings 59, 60 in theescape plate 26 and the escape cock 21, and itself supports the escapewheel 6!. This escape wheel (Figs. 3, 4 and 5) has the teeth 62 partlyextending from the rim in its plane and partly extending above thisplane: this width of each tooth permits engagement of the impulse stoneand the locking stone H1 at different levels. The escape stafi 58 hasthe pinion 63 which in the chronometer assembly is in mesh with thefourth wheel |5a of the train (Fig. 5).

The detent blade 65 is supported by the detent blade spring 66 connectedto the detent foot 61. An upper projection '68 (Fig. 5) of the blade 65carries a pipe 89 (Fig. 4) in which is secured the locking stone T0. Theoperating end of the stone is thus clear of the pipe 69 and the blade65, for visual inspection of its position. A lower projection H isspaced along the blade 65 from the stud 69 and rests, during the lockingperiod, against the position adjusting screw 12, which is also out ofalignment with the stone Ill. The passing spring 13, sometimes calledthe gold spring, is secured to the detent blade b the screw 14 andextends along the blade between the stud 69 and the screw 12, andprojects beyond the top of the detent horn for engagement by thedischarge stone 55. It is preferred to provide a thinned portion 13c onthe passing spring to localize most of the bending at a point as far aspossible from the active end.

The detent foot 61 is guided b locating dowels 61d fixed to the block 16having a slot ll through which extends the securing screw 18 that holdsthe block against the lower face of the escape plate 26, and maintainsthe tongue 16a of block 16 in guided position in a groove 26a in theplate 25. An adjusting screw 19 has a collar 80 which engages a notch inthe escape 26 whereby the screw 19 is held against axial movement but byits threaded engagement with the block '16 it effects longitudinaladjustment of the block with the detent structures. The screw 18 whentightened serves to hold the block 16 securely in adjusted position. Thebar 8| is formed as a part of the block 16 and supports the adjustingscrew 72: thus, as the block 76 and detent blade are moved by screw 19,the screw 12 and the projection 10 are retained in proper correlatedposition.

The impulse stone 53 engages the upper ends oi the teeth 62, while thelocking stone 1!! engages the lower ends of these teeth (Fig. 5). Thus,dif- '4 ferent parts of the escape wheel act for impulse and forlocking, so that the wear is distributed over the surfaces.

The wear upon the escape wheel teeth differs accordingly as the contactis made by the impulse stone or the locking stone. The impulse stoneswings in an arc while being contacted by the escape teeth: part of thismovement is shown in Fig. 6 as the parts pass from the dotted to thefull line position, from which it will be seen that the wear is greaterat the outer edge of the tooth than at points along its face, wherebythe wear leads to a shape as indicated by the dash line 95. On the otherhand, the locking stone T0 is preferably adjusted so that it receivesthe escape tooth 62 flatwise over a large area at the instant of locking(Fig. 7). During unlocking, when the detent blade is moved outwardl bythe discharge stone, the locking stone (0 is drawn along the face of thetooth 62, so that the wear thereon is essentially uniform as thepressure does not Vary greatly. Hence the engaged portion of the surfaceof tooth 62 during unlocking normally wears along a dot-dash line 96,which is essentially parallel to the tooth face itself. This differencein wear causes difliculty when both the impulse stone 53 and the lockingstone ill act on the same tooth surface, as the curvature produced bythe wear against the stone 53 leads to a shape illustrated by the line95, wherewith the escape wheel will creep forward as the locking stone10 is withdrawn and the discharge action is made irregular. Thus thesegregation of functions to the separate parts of the individual teeth52 assures a longer life, and a more accurate service during the life ofthe parts. Each tooth part can wear to that shape which each actiontends to produce, without complex error arising by the action of theimpulse stone in causing wear of the tooth part engaged by thedischarging stone, and vice versa. Thus, when the cooperating parts havebeen broken in by initial running, the later wear is very slow andregular.

The balance cock 25 is cut away as indicated by the line in Fig. 2, toprovide a hole opposite the impulse stone 53, the locking stone ID, thecooperating portions of the periphery of the escape wheel BI, andadjacent parts of other structures. Similarly, the escape cook 21 is cutaway as indicated by the line ill-9| (Fig. 4) for likewise exposing thesame parts. The spoke arm 37 is of limited size at its center so thatthe impulse stone 53 projects beyond it, into alignment with theseholes, at the moment of impulse reception. The impulse stone 53 and thelocking stone 1c are preferably of sapphire, ruby or other coloredlight-transmitting and wear-resisting materials. Light may be projectedas a beam marked by the circle 92 in Fig. 2, through the escapement unitin a direction generally parallel to the axes of the staffs, and thengathered by a focussing system to form an enlarged image upon a patternsheet; and the image of the stone and detent observed in conjunctionwith the escape wheel. Thus, the relative positions and operations ofthe parts of the escapement unit can be studied during the adjustments,and the parts brought to the positions indicated by the pattern sheet.

After assembly of the parts, the operator adjusts the staffs to properend shake and positions the block 16 so that the discharge stone 55 doesnot engage the horn of detent blade 65. It is customary to do this whilethe illustrated escapement unit is free of the other parts of thechronometer assembly, andto employ alight projection system as set outin Fig. 8, with. a fixture I in which this unit is mounted inpredetermined position. In so mounting it, the parts are brought intoengagement with a fourth wheel |a in the projector which can be drivenby appropriate power sourcesuch as a coil spring Illl The lamp I02 andcondensing lens assembly I03 project a beam of light I04 through theescapement: and the lens system I05 and mirrors I06, I01 cause theenlarged image of the parts within circle 92 of Fig. 2 to appear uponthe pattern sheet I08.

The work of assembling the parts brings the escapement into approximatebeat. The operations of adjusting to correct operation and rate may beaccomplished asfollows:

(a) The clearance of the impulse stone is established by releasing theclamping screw 18 and rotating the adjusting screw 19 to move thelocking stone [0 and thus to rotate the escape wheel 6| until the twoteeth nearest the impulse roller have equal impulse stone clearances.The amount of this movement is small because of the accuracy ofmanufacture and careful inspection of the parts: and never brings thehorn of detent blade 65 into the path of the discharge stone. Theclamping screw 18 is tightened to fix the adjustment.

(b) The lock or amount of overlap of the looking stone H1 with theengaged escape tooth B2 is adjusted by the screw 12. Thus, the detentblade 65, 66, 61 is now in position.

(0) The liftof the gold or passing spring 13 is now adjusted by shapingthe end of the spring and, with the screw 14 loose, mOVing the spring 13endwise towards or from the balance staff until a desired lift andrelease effect is observed as the rollers are rocked. The screw 14 istightened to secure the spring 13 in position.

(d) The discharge roller 54 is turned on the staff 32 until the tworoller stones are at the correct relative angle. The correct positionand unlocking action is present when an escape tooth 62 drops onto theimpulse stone when this stone 53 isin a definite position drawn on theprojection diagram 108-, for example as shown by the full lines 53 inFig, 6. This diagram is prepared by indicating thereon the end positionsof the image of the impulse stone 53 when a standard and properlyadjusted balance is oscillating in beat; and the full line position inFig. 6 is then drawn as that at which the full angle of movement of theimpulse stone clearing engagement with an escape wheel tooth 62 isbisected by the line of centers of the escape and balance. The impulseroller 52 in preferred construction is so tightly fitted to the staffthat it does not turn thereon; if slippage of the impulse stone occurswhile the discharge roller is being turned for adjustment, a beatreadjustment is necessary. Some operators prefer to put the escapementin beat before this adjustment (:1) is accomplished, to ascertain theprevailing relationships of the staff and its other parts with respectto the rollers.

(e) The detent lift is checked by rotating the balance in acounterclockwise direction in Fig. 4 and observing the action as thedischarge stone 55 acts through the detent to disengage the lockingstone 1'0 from the escape wheel tooth. These effects are observed by theprojection image and its relation to the standard pattern. If anunsatisfactory action is observed, adjustments (a), (b) and (c) arerechecked and corrections made.

(I) The escapement is put in beatby turning the'hairspring collet on thebalance staff. When the: escapement is in beat, the position of theimpulse stone image on the projection diagram should coincide with theposition thereon for the balance parts at rest (Fig. 6).

(g) When these static adjustments have been made, power is applied tothe escape wheel through a fourth wheel l5a from a temporary drivespring IUI (Fig. 8); and the operation of the system observed by theprojected image. Due .to the rapidity of movement of parts and thedetention. ofv the escape wheel 6| by the locking stone waiter eachbalance movement, a stroboscopic effect occurs and the dynamic behaviorof. the parts can be observed during actuation and slight adjustmentsmade for any error appearing during this test of operation. In practice,a relatively. few revolutions of the escape wheel will suflice for thisat initial assembly, with due preliminary care in manufacture andinspection of the escape wheel. During this time, also,localized'irregularities of other cooperating parts may appear, thusindicating the place and nature of the trouble and permitting furtherstatic studies, and studies while slowly moving parts manually:replacements and corrections are then accomplished before assemblinginto a chronometer.

The balance masses can noW be adjusted under varying conditions oftemperature, etc., so that the moment of inertia of the balance Wheelremains constant under the various conditions of probable service. Whenthis has been accomplished, the unit can be packaged and handled as areplacement for a faulty unit in an existing chronometer, or can itselfbe introduced into a new chronometer which is being manufactured.

The operation of the escapement may be briefly described as follows:

The main spring performs its usual fufictibh of driving the train andoperating the hands. The train includes a fourth wheel l5a which isengaged with the pinion 63 on the escape staff 58. With the parts shownin the position of Fig. 4, one tooth 52 of the escape wheel 6! is beingdetained by the locking stone 10. In this figure the balance hascompleted its counter-clockwise movement and is now rocking in aclockwise direction. The impulse stone 53 clears the two teeth 62 whichare opposite its path. The discharge stone 55 will shortly (afterleaving the position of Fig. 4) engage the passing spring 13 and movepast this spring, whereupon the spring will return to the position shownin Fig. 4.

When the balance completes its movement in a clockwise direction, itbegins to return in the working or counter-clockwise stroke. The impulsestone 53 moves to the position 53:): shown in dotted lines in Fig. 4 andattains this dotted position at essentially the same instant when thedischarge stone 55 has engaged the passing spring 73 and moved thedetent until the locking stone 10 releases the tooth 62 with which ithas been engaged. The escape wheel BI is now free to move: and one ofits teeth immediately engages the impulse stone 53 at essentially theposition 53a: and delivers the maintaining impulse to the balancesystem. By effectingthe adjustments as prescribed above, the impulseangle, or angle of balance movement during the reception of impulse, canbe so located as to be bisected by the dead center line, wherewith theretarding and advancing effects thereof neutralize each other.

As the discharge stone 55 releases the passing spring 13, the detentmoves backward and again engages the screw 12 which provides a stop, sothat the locking stone is in position to receive the next tooth 62 andthus lock the escape wheel again.

It may be pointed out that the engagement of each tooth 82 with thelocking stone 10 produces a couple of forces fo the reason that thisengagement occurs out of the line of the detent blade Q5 and its spring56, so that there is a bending or rocking of the detent system with theend of screw 12 forming a rest over which there is a slight longitudinalsliding motion of the projection H of the detent blade 65. This slightyield cushions the impact of the tooth 62 upon the locls'f' stone it andserves to reduce the fatigue wear upon the teeth, and the possibility offracturing the locking stone 10.

It is obvious that the invention may be employed in other ways withinthe scope of the pending claims.

We claim:

1. A chronometer escapement comprising plate and cock structures, anescape wheel pivoted on said structures, a balance assembly pivoted onsaid structures, the balance assembly including an im ulse stoneactuated from the escape wheel and a discharge stone, and a detentassembly including a detent blade and a locking stone carried by saidblade and also including a block guided by the plate for longitudinaladjusting movement with the detent blade thereon, means for clampingsaid block to the plate in adjusted position, said detent assembly alsoincluding a part positioned for engagement and actuation by saiddischarge stone whereby the detent blade is moved for releasing thelocking stone from the detent wheel; said plate and cook structuresbeing constructed and arranged with spaces effective to ermit light raysto pass in a direction essentially parallel to the escape wheel axis,said impulse stone and locking stone being attached in posi tions offsetrespectively from adjacent opaque parts of the balance and the detentassembly and located opposite said spaces, said escape wheel beingconstructed and located in said structures so that it projects into thepath of said light rays, whereby visual inspection may be made ofrelated static and stroboscopic-dynamic concurrent positions of theescape wheel, impulse stone, and locking stone.

2. A. chronozneter escapement having a toothed escap 'hcel, a balanceassembly including an impu! stone actuated from the escape wheel and adischarge stone, and a detent assembly including a detent blade, adetent sprin supporting the detent blade, a locking stone mounted on 8the detent blade and efiective for detaining the escape wheel and adevice on the detent blade actuated by the discharge stone and effectivefor moving the locking stone toward and from the axis of the escapewheel, characterized in that the impulse stone and locking stone arearranged at different radial planes through the escape wheel whereby thesaid stones act upon different portions of the teeth of said escapewheel, said teeth having essentially identical sections at the planes ofengagement of said stones therewith.

3. A removable escapement structure for a chronometer having a trainplate provided with a notch; said structure including a balance cockportion overlying the train plate and secured thereto, a second portionfitted in said notch, and a third and depending portion; said structureincluding bearings for the balance and escape assemblies, and alsoincluding a support for the detent assembly, said second portion andsaid support having interengaging guide parts for limiting the movementof the support to longitudinal adjustment along said structure towardand from the balance assembly, and means for fixing said support inadjusted position, and baance and escape assemblies in said bearings,said balance assembly including a balance spring having its fixed endconnected to said balance cock portion.

GEORGE G. ENSIGN. ROBERT R. LAWSON. EARL H. SCHAEFER. WENZEL M. WOCHOS,JR.

REFERENCES CITED The following references are cl record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 168,582 Potter Oct. 11, 1875281,758 Fitt July 2 1, 1883 1,0 16 McAlpine Aug. 29, 1893 689,115Peabody Dec. 17, 1901 808,631 Brown Jan. 2, 1906 1,091,261 Walker Mar.24, 1914 FOREIGN PATENTS Number Country Date 40 Great Britain of 1852 2,32 Great Britain of 1796 7,350 Great Britain of 1837 22,363 GreatBritain of 1897 165,887 Switzerland Feb. 16, 1934 OTHER REFERENCES TheMarine Chronometer, Gould, 1923, J. D. Potter, Minories, London.

